Davis, Carl L. 1927. Development of the human heart from its first appearance to the stage found in embryos of twenty somites. Contrib Embryol. Carnegie Institution of Washington. 19:245-284.

DeVries, P.A., and Saunders, J.B. deC.M. 1962. Development of the ventricles and spiral outflow tract in the human heart - a contribution to the development of the human heart from age group IX to age group XV. Contrib Embryol. Carnegie Institution of Washington. 37:87-114.

Gardner, E., and O'Rahilly, R. 1976. The nerve supply and conducting system of the human heart at the end of the embryonic period proper. Journal of Anatomy. 121:571-587.

Hertig, A.T., and Rock, J. 1945. Two human ova of the pre-villous stage, having a development age of about eight and nine days respectively. Contrib Embryol. Carnegie Institution of Washington. 33:169-186.

Hertig, A.T., and Rock, J. 1949. Two human ova of the pre-villous stage, having a development age of about seven and nine days respectively. Contrib Embryol. Carnegie Institution of Washington. 31:65-84.

Hertig, A.T., and Rock, J. 1941. Two human ova of the pre-villous stage, having an ovulation age of about eleven and twelve days respectively. Contrib Embryol. Carnegie Institution of Washington. 29:127-156.

Hertig, A.T., Rock, J., Adams, E.C., and Mulligan, W.J. 1954. On the preimplantation stages of the human ovum: A description of four normal and four abnormal specimens ranging from the second to the fifth day of development. Contrib Embryol. Carnegie Institution of Washington. 35:199-220.

Müller, F., O'Rahilly, R, and Tucker, J. A. 1981. The human larynx at the end of the embryonic period proper: 1. The laryngeal and infrahyoid muscles and their innervation. Acta Otolaryngol. 91:323-336.